He was likely wearing subdued wings. In the field, shiny rank insignia is drab. Silver is black, and gold is brown or bronzish. As far as why people wear subdued wings with anodized rank, I have no idea. Actual gold shouldn't tarnish like silver.
Maybe tarnish is the wrong word, since like you said, gold shouldn't do that. How about "aged and salty?" My gold wings are a different color (darker and more aged) than the standard anodized NEX wings, but that has come with 15 years of not doing anything to them.
But ltedge and BzB are probably on target.